Excessive zinc in diet induces leptin resistance in Wistar rat through increased uptake of nutrients at intestinal level

Association Between Serum Zinc and Non-Alcoholic Fatty Liver Disease and Advanced Liver Fibrosis: NHANES 2011-2016

Limited and inconclusive evidence exists regarding the correlation between serum zinc levels and non-alcoholic fatty liver disease (NAFLD) and advanced fibrosis. The objective of this cross-sectional study was to investigate the association between serum zinc concentration and both NAFLD and advanced liver fibrosis among the United States (US) adults. 3398 subjects from National Health and Nutrition Examination Survey (NHANES) 2011-2016 were included. Serum zinc concentration was measured by inductively coupled plasma dynamic reaction cell mass spectrometry (ICP-DRC-MS). NAFLD was diagnosed with Hepatic Steatosis Index (HSI), and advanced fibrosis risk was assessed by NAFLD Fibrosis Score (NFS). Weighted logistic regression and restricted cubic splines (RCS) were used to examine the association between serum zinc concentration and NAFLD and advanced fibrosis. Linear trend tests were conducted by incorporating the median of serum zinc quartiles as a continuous variable in the models. We employed sensitivity analysis and subgroup analysis to enhance the robustness of our results. The results from the RCS regression revealed no evident nonlinear relationship between serum zinc concentration and the presence of NAFLD and advanced fibrosis (p-nonlinear > 0.05). Compared with those in the lowest quartile (Q1) of serum zinc concentrations, the odds ratios (95% confidence intervals) of NAFLD were 1.49 (0.89,2.49) in Q2, 0.99 (0.68,1.45) in Q3, and 2.00 (1.40,2.86) in Q4 (p-trend = 0.002). Similarly, the odds ratios (95% confidence intervals) for advanced fibrosis in Q2-4 compared to Q1 were 0.86 (0.50,1.47), 0.60 (0.26,1.39), and 0.41 (0.21,0.77), respectively (p-trend = 0.006). Subgroup analyses and sensitivity analyses reinforce the same conclusion. The investigation revealed a positive linear relationship between serum zinc concentrations and the probability of developing NAFLD. Conversely, an inverse correlation was observed between serum zinc concentrations and the incidence of advanced liver fibrosis among individuals diagnosed with NAFLD.

High Serum Zinc Concentration Accelerates Progression of Isolated Impaired Glucose Tolerance to Type 2 Diabetes: A Cohort Study

This cohort study investigated the possible association between serum zinc (SZn) concentration and the risk of progression to type 2 diabetes (T2D) in subjects with isolated impaired glucose tolerance (iIGT). SZn was measured in 198 subjects with iIGT (mean age: 53.0 ± 14.4 years and 33.8% were men) at baseline (2009-2011), and they were followed for developing T2D up to 2017. A univariate unrestricted regression spline (UVRS) was used to assess the potential non-linear association and identify the best placement of SZn knots related to the incidence of T2D. Multivariable Cox proportional hazard models were used to calculate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) of incident T2D across the best placement of knots. The predictive power of SZn for developing T2D was determined using receiver operating characteristic (ROC) analyses, and the Youden index identified the optimal cut-off values. Mean baseline SZn concentration was 115 ± 42.9 µg/dL. Over a median 6-year follow-up, 27.8% of subjects with iIGT developed T2D. A non-linear association was observed between SZn and the incidence of T2D (pnon-linearity from the likelihood ratio test < 0.001). Higher SZn ≥ 106 µg/dL and ≥ 134 µg/dL was associated with elevated risk of T2D by 127% (HR = 2.27, 95% CI = 1.01-5.10) and 144% (HR = 2.44, 95% CI = 1.05-5.69), respectively. According to the crude and multivariate-adjusted ROC analyses, the optimal cut-off values of SZn to identify incident T2D were ≥ 87.5 µg/dL (sensitivity of 83.6%, specificity of 30.1%) and 151.8 µg/dL (sensitivity of 64.4%, specificity of 76.3%), respectively. Elevated SZn levels at baseline were positively associated with the future risk of T2D in subjects with iIGT.

Age-dependent interaction between serum zinc and triglyceride-glucose index among American adults: National Health and Nutrition Examination Survey

Introduction

Zinc plays a crucial role in glucose metabolism. The association between serum zinc and insulin resistance has recently been investigated as well, but the findings are inconsistent. The triglyceride-glucose index (TyG) is frequently utilized in epidemiological research to assess insulin resistance. The association between serum zinc levels and TyG has not yet been explored. Therefore, we designed this cross-sectional study to assess the relationship between serum zinc and TyG in adults using data from the National Health and Nutrition Examination Survey (NHANES).

Methods

A cross-sectional analysis was performed on 1,610 adults aged ≥20 years who participated in the National Health and Nutrition Examination Survey (NHANES) 2011-2016. The participants were stratified by age, and the differences in log-transformed serum zinc quartiles and TyG were further evaluated in age groups <60 years and ≥60 years using multivariable linear regression with an interaction test. Additionally, a restricted cubic spline (RCS) model was employed to examine the dose-response relationships between log-transformed serum zinc and TyG.

Results

In this cross-sectional study, a significant interaction was observed between log-transformed serum zinc and TyG in individuals aged <60 years and those aged ≥60 years when log-transformed serum zinc was transformed into a categorical variable (P-value for the likelihood ratio test for the interaction was P = 0.017). Additionally, in the fully adjusted analyses, the association between log-transformed serum zinc and TyG in the age <60 years group demonstrated a J-shaped nonlinear pattern (P for nonlinearity = 0.014), with an inflection point at ~1.94 μg/dL. While in the age ≥60 years group, it exhibited an inverted-L shaped nonlinear pattern (P for nonlinearity < 0.001***).

Conclusion

There is a significant relationship between log-transformed serum zinc and TyG in adults in the United States, with age potentially influencing this association. Further prospective studies are needed to offer additional evidence and insights into these findings.

Association of composite dietary antioxidant index with circadian syndrome: evidence from NHANES

Background

The Circadian Syndrome (CircS) has been linked to various chronic diseases. However, the relationship between composite dietary antioxidant index (CDAI) and CircS has remained unexplored. This study aimed to investigate the potential association between CDAI and CircS.

Methods

Cross-sectional analyses were based on the National Health and Nutrition Examination Survey (NHANES) 2005-2018. Dietary consumption was assessed via the 24-h diet recall method and CDAI was computed following a validated approach involving six antioxidants. CircS was defined based on metabolic syndrome components, supplemented by short sleep duration and depressive symptoms. The relationship between CDAI and CircS was examined using weighted multivariable logistic regression and subgroup analyses. Additionally, restricted cubic spline (RCS) regression was employed to investigate potential nonlinear correlations.

Results

Among 11,048 subjects included (mean age 47.57 years), 2,733 (weighted prevalence = 22.13%) were reported to have CircS. Logistic regression revealed that the highest quartile of CDAI was inversely associated with the risk of CircS {odds ratio (OR) [95% CI = 0.69 (0.55-0.87)]} and the risk of depression [OR = 0.59 (0.48-0.72)], short sleep duration [OR = 0.54 (0.41-0.70)], elevated fasting glucose [OR = 0.80 (0.65-0.98)], elevated triglycerides (TG) [OR = 0.74 (0.59-0.92)], elevated waist circumference [OR = 0.65, (0.52-0.80)] and reduced high-density lipoprotein cholesterol (HDL-C) [OR = 0.75 (0.61-0.92)], respectively. A dose-response gradient in odds of CircS components was noted as CDAI levels increased, particularly with depression and short sleep duration. RCS showed a non-linear relationship between CDAI and CircS, with a U-shaped correlation found between Zinc and CircS (inflection point 12.63). Subgroup analysis showed BMI modified the inverse association between CDAI and CircS (p for interaction = 0.003).

Conclusion

This study revealed a non-linear and negative association between CDAI and CircS risk, with a U-shaped correlation observed between Zinc and CircS. Obese individuals might not benefit from excessively high CDAI. The results suggest that a higher CDAI score was correlated with a decreased risk of CircS.

Multifunctional nanocoatings with synergistic controlled release of zinc ions and cytokines for precise modulation of vascular intimal reconstruction

Vascular stent implantation remains the major therapeutic method for cardiovascular diseases currently. We here introduced crucial biological functional biological function factors (SDF-1α, VEGF) and vital metal ions (Zn2+) into the stent surface to explore their synergistic effect in the microenvironment. The combination of the different factors is known to effectively regulate cellular inflammatory response and selectively regulate cell biological behavior. Meanwhile, in the implemented method, VEGF and Zn2+ were loaded into heparin and poly-l-lysine (Hep-PLL) nanoparticles, ensuring a controlled release of functional molecules with a multi-factor synergistic effect and excellent biological functions in vitro and in vivo. Notably, after 150 days of implantation of the modified stent in rabbits, a thin and smooth new intima was obtained. This study offers a new idea for constructing a modified surface microenvironment and promoting tissue repair.

Habitual intake of iron, copper, and zinc and the risk of type 2 diabetes in a prospective cohort: The CAVAS (Cardiovascular Disease Association Study)

BACKGROUND AND AIMS

Unlike iron, evidence of the association between dietary copper and zinc intake and type 2 diabetes (T2D) risk is limited. This study aimed to examine the prospective associations of dietary intake of iron (total, plant-based, and animal-based), copper, and zinc with T2D risk among adults aged ≥40 years.

METHODS AND RESULTS

For 16,666 participants, dietary intakes (baseline, cumulative average, and most recent) of iron, copper, and zinc were calculated from repeated food frequency questionnaires; a modified Poisson regression model with a robust error estimator was conducted. In men, positive associations between T2D and baseline dietary intake of Cu and Zn, cumulative average dietary intake of Fe (total and animal-based), Cu and Zn, and most recent dietary intake of Fe (total, plant-based, and animal-based), Cu, and Zn [most recent diet: for total Fe, IRR(95%CI) = 1.93 (1.41-2.64); for plant-based Fe, 1.56 (1.15-2.11); for animal-based Fe, 1.44 (1.09-1.90); for Cu, 3.17 (2.33-4.30); for Zn, 2.18 (1.64-2.89)] were observed, where as in women, there were positive associations of only cumulative average dietary Zn intake and most recent dietary intake of plant-based Fe, Cu, and Zn [most recent diet: for plant-based Fe, 1.30 (1.01-1.68); for Cu, 1.62 (1.27-2.08); for Zn, 2.07 (1.61-2.66)].

CONCLUSION

Dietary intakes of iron (total, plant-based, and animal-based), copper, and zinc may be positively associated with T2D risk. These positive associations are predominantly observed in most recent diet and appear to be stronger compared to baseline and cumulative average diet.

Effect of mineral-vitamin premix supplementation on behavioral, performance, hormonal, oxidative stress, and serum biochemical profiles on rutting male Camelus dromedarius in Egypt

Introduction

The rutting period imposes a stressful condition on male camels, which results in elevated serum cortisol levels and alterations in their sexual behavior. Therefore, the current work was carried out to investigate the effect of mineral-vitamin premix supplementation on behavior, reproductive performance, hormones, serum oxidative stress profile, and other serum biochemical parameters of Camelus dromedarius during the breeding season.

Methods

Fourteen mature, fertile male Camelus dromedarius were divided into two groups, a control group (n = 7) and a mineral-vitamin premix group (n = 7). The present study lasted for 95 days during the rutting period (1st February to 5th May). Each camel in the premix group received a daily diet of 50 g of mineral-vitamin premix throughout the whole rutting period, during which the frequencies and durations of the following behaviors: maintenance, posture, aggressiveness, and sexual activity were collected every 20 min. At the end of the study, blood samples were collected.

Results

Results revealed that the premix group showed higher (P < 0.05) maintenance (feeding and rumination), standing, and overall sexual desire-related behavior frequency, besides more times (P < 0.001) for rumination, standing, walking, and lying while showing lower (P < 0.001) frequencies of overall aggressive behaviors than the control group. The serum concentration of malondialdehyde, nitric oxide, cortisol, blood glucose, and urea evidenced a significant decrease in the premix group compared with the control one, while significantly elevated levels of reduced glutathione, testosterone, total antioxidant capacity, triiodothyronine, and thyroxin, total protein, albumin, globulin, calcium, phosphorus, potassium, and magnesium were recorded in the premix group in comparison with the control.

Conclusion

It could be concluded that daily dietary supplementation of 50 g of mineral-vitamin premix to male camels during the breeding season is necessary to overcome the oxidative stress and serum cortisol concentration with a subsequent decrease in aggressive behavior and improvement to testosterone level in blood, body condition score and body weight gain.

The association between plasma zinc concentrations and markers of glucose metabolism in adults in Cameroon

An abnormal Zn status has been suggested to play a role in the pathogenesis of type 2 diabetes. However, epidemiological studies of the relationship between plasma Zn concentrations and diabetes are sparse and inconclusive. We aimed to investigate the association between plasma Zn concentrations and glycaemic markers (fasting glucose, 2-h glucose and homeostatic model assessment of insulin resistance) in rural and urban Cameroon. We studied 596 healthy adults (63·3 % women) aged 25-55 years in a population-based cross-sectional study. The mean plasma Zn concentration was 13·7 ± 2·7 µmol/L overall, with higher levels in men (14·4 ± 2·9 µmol/l) than in women (13·2 ± 2·6 µmol/l), P-value < 0·0001. There was an inverse relationship between tertiles of plasma Zn and 2-h glucose concentrations (P-value for linear trend = 0·002). The difference in 2-h glucose between those in the highest tertile of plasma Zn compared to the lowest was -0·63 (95 % CI - 1·02, -0·23) mmol/l. This remained significant after adjusting for age, sex, smoking status, alcohol intake, education level, area of residence, adiposity and objectively measured physical activity -0·43(-0·82, -0·04). Similar inverse associations were observed between plasma Zn concentrations and fasting glucose and homeostatic model assessment of insulin resistance when adjusted for socio-demographic and health-related behavioural characteristics. The current findings of an inverse association between plasma Zn concentrations and several markers of glucose homeostasis, together with growing evidence from intervention studies, suggest a role for Zn in glucose metabolism. If supported by further evidence, strategies to improve Zn status in populations may provide a cheap public health prevention approach for diabetes.

Zinc nutrition and dietary zinc supplements

As the second most abundant trace element in the human body, zinc nutrition is constantly a hot topic. More than one-third population is suffering zinc deficiency, which results in various types of diseases or nutritional deficiencies. Traditional ways of zinc supplementation seem with low absorption rates and significant side effects. Zinc supplements with dietary components are easily accessible and improve zinc utilization rate significantly. Also, mechanisms of maintaining zinc homeostasis are of broad interest. The present review focuses on zinc nutrition in human health in inductive methods. Mainly elaborate on different diseases relating to zinc disorder, highlighting the impact on the immune system and the recent COVID-19. Then raise food-derived zinc-binding compounds, including protein, peptide, polysaccharide, and polyphenol, and also analyze their possibilities to serve as zinc complementary. Finally, illustrate the way to maintain zinc homeostasis and the corresponding mechanisms. The review provides data information for maintaining zinc homeostasis with the food-derived matrix.

Excess dietary zinc drives a Cushing's-like syndrome in ovariectomized mice - Implications for postmenopausal obesity

Postmenopausal women have an increased risk of obesity, but the underlying cause is not clear. We unexpectedly found that excess dietary zinc induced severe obesity and a Cushing's-like syndrome without increased food intake in ovariectomized (Ovx) but not in sham-operated mice. Zinc accumulated in the adrenal glands and inhibited adrenal 17,20-lyase activity and steroid synthesis. As adrenal steroids are the only source of estrogen in Ovx mice, estrogen deficiency induced adrenal hyperplasia, glucocorticoid overproduction, and consequent development of a Cushing's-like syndrome. Adrenal steroid supplementation prevented the effects of zinc. Plasma zinc was positively correlated with cortisol level and negatively correlated with the levels of adrenal steroids and estrogen in obese postmenopausal women. The finding of a link between dietary zinc, estrogen deficiency, and postmenopausal obesity, implies that postmenopausal obesity might be prevented by supplementation with a adrenal steroid and avoiding excess dietary zinc.

Serum zinc concentrations and prediabetes and diabetes in the general population

The association between serum zinc and diabetes development remains uncertain. We examined the associations between serum zinc and prediabetes and diabetes, and adult participants (≥ 20 years) from the 2011-2016 National Health and Nutrition Examination Survey. Serum zinc concentrations were measured with inductively coupled plasma dynamic reaction cell mass spectrometry. Prediabetes and diabetes were defined through questionnaires and fasting plasma glucose and hemoglobin A_1c levels. Weighted logistic regression and restricted cubic splines were adopted to explore the dose-response relationships between serum zinc concentrations and prediabetes and diabetes. Comparing the highest to lowest quartile of serum zinc concentrations, the multivariable-adjusted odds ratio (95% confidence interval) of prediabetes and diabetes was 3.24 (2.33-4.52, P_{for trend} < 0.01) and 1.64 (1.27-2.11, P_{for trend} < 0.01), respectively. In stratified analysis by sex, the association between serum zinc concentrations and prediabetes was found in both men (3.83 (2.60-5.66), P_{for trend} < 0.01) and women (2.41 (1.51-3.87), P_{for trend} < 0.01), and the association between serum zinc concentrations and diabetes was also found in both men (2.05 (1.34-3.13), P_{for trend} < 0.01) and women (1.65 (1.07-2.56), P_{for trend} = 0.15). The association between serum zinc and prediabetes was consistent in stratified analyses by body mass index and hypertension, and the association with diabetes was also found in subjects with hypertension. Restricted cubic splines showed that the relationships between serum zinc concentrations and prediabetes and diabetes were linear, respectively. In conclusion, serum zinc concentrations were positively associated with prediabetes and diabetes in the general population, and the associations were linear. The findings need to be confirmed by prospective cohort studies.

U-shaped Association Between Dietary Zinc Intake and New-onset Diabetes: A Nationwide Cohort Study in China

AIMS

We aimed to investigate the relationship of dietary zinc intake with new-onset diabetes among Chinese adults.

MATERIALS AND METHODS

A total of 16 257 participants who were free of diabetes at baseline from the China Health and Nutrition Survey were included. Dietary intake was measured by 3 consecutive 24-hour dietary recalls combined with a household food inventory. Participants with self-reported physician-diagnosed diabetes, or fasting glucose ≥ 7.0 mmol/L, or glycated hemoglobin ≥ 6.5% during the follow-up were defined as having new-onset diabetes.

RESULTS

A total of 1097 participants developed new-onset diabetes during a median follow-up duration of 9.0 years. Overall, the association between dietary zinc intake and new-onset diabetes followed a U-shape (P for nonlinearity < 0.001). The risk of new-onset diabetes was significantly lower in participants with zinc intake < 9.1 mg/day (per mg/day: hazard ratio [HR], 0.73; 95% CI, 0.60-0.88), and higher in those with zinc intake ≥ 9.1 mg/day (per mg/day: HR, 1.10; 95% CI, 1.07-1.13). Consistently, when dietary zinc intake was assessed as deciles, compared with those in deciles 2-8 (8.9 -<12.2 mg/day), the risk of new-onset diabetes was higher for decile 1 (<8.9 mg/day: HR, 1.29; 95% CI, 1.04-1.62), and deciles 9 to 10 (≥12.2 mg/day: HR, 1.62; 95% CI, 1.38-1.90). Similar U-shaped relations were found for plant-derived or animal-derived zinc intake with new-onset diabetes (all P for nonlinearity < 0.001).

CONCLUSIONS

There was a U-shaped association between dietary zinc intake and new-onset diabetes in general Chinese adults, with an inflection point at about 9.1 mg/day.

Associations of plasma metal levels with type 2 diabetes and the mediating effects of microRNAs

The present study aims to determine the associations of multiple plasma metal levels and plasma microRNAs (miRNAs) with diabetes risk, and further explore the mediating effects of plasma miRNAs on the associations of plasma metal with diabetes risk. We detected plasma levels of 23 metals by inductively coupled plasma mass spectrometry (ICP-MS) among 94 newly diagnosed and untreated diabetic cases and 94 healthy controls. The plasma miRNAs were examined by microRNA Array screening and Taqman real-time PCR validation among the same study population. The multivariate logistic regression models were employed to explore the associations of plasma metal and miRNAs levels with diabetes risk. Generalized linear regression models were utilized to investigate the relationships between plasma metal and plasma miRNAs, and mediation analysis was used to assess the mediating effects of plasma miRNAs on the relationships between plasma metals and diabetes risk. Plasma aluminum (Al), titanium (Ti), copper (Cu), zinc (Zn), selenium (Se), rubidium (Rb), strontium (Sr), barium (Ba), and Thallium (Tl) levels were correlated with elevated diabetic risk while molybdenum (Mo) with decreased diabetic risk (P < 0.05 after FDR multiple correction). MiR-122-5p and miR-3141 were positively associated with diabetes risk (all P < 0.05). Ti, Cu, and Zn were positively correlated with miR-122-5p (P = 0.001, 0.028 and 0.004 respectively). Ti, Cu, and Se were positively correlated with miR-3141 (P = 0.003, 0.015, and 0.031 respectively). In addition, Zn was positively correlated with miR-193b-3p (P = 0.002). Ti was negatively correlated with miR-26b-3p (P = 0.016), while Mo and miR-26b-3p were positively correlated (P = 0.042). In the mediation analysis, miR-122-5p mediated 48.0% of the association between Ti and diabetes risk. The biological mechanisms of the association are needed to be explored in further studies.

Alterations of serum trace elements in patients with type 2 diabetes

OBJECTIVE

The aim of the present study is to investigate the association of trace elements and the risk of type 2 diabetes mellitus.

DESIGN AND METHODS

The 1837 participants (637 men and 1200 women) aged 40-70 were from a cross-sectional community-based study performed in downtown Shanghai. All the participants without diabetes mellitus history underwent a 75-g OGTT. The participants with diabetes mellitus took 100g steamed bread as the substitute. The fasting and OGTT 2h or postprandial 2h venous blood samples were collected. Blood glucose levels, fasting serum insulin concentrations, lipid profiles, HbA1C and 19 trace elements including magnesium, copper, zinc and selenium and so on were assayed.

RESULTS

Of all the 1837 studied subjects, 510 subjects had diabetes mellitus (191 male, 319 female). Serum magnesium levels were decreased statistically (p<0.05), but serum copper, zinc and selenium levels were significantly increased in subjects with diabetes mellitus compared to non-diabetic subjects (p<0.01 for copper, p<0.001 for zinc and selenium). Logistic regression analysis showed that serum magnesium was negatively associated with diabetes (p<0.05) and serum copper, zinc, and selenium were all positively associated with diabetes (p<0.05 for copper, p<0.001 for both zinc and selenium). Correlation analysis showed a remarkable correlation between blood glucose, HbA1C and serum magnesium, copper, zinc, and selenium (p<0.01 for zinc, p<0.001 for copper, zinc and selenium).

CONCLUSIONS

Serum magnesium levels are decreased and serum copper, zinc and selenium levels are elevated in patients with type 2 diabetes mellitus.

Association between serum zinc and later development of metabolic syndrome in middle aged and older men: The Kuopio Ischaemic Heart Disease Risk Factor Study

OBJECTIVE

The aim of this study was to investigate associations of serum zinc with incident metabolic syndrome and its components in middle-aged and older Finnish men.

METHODS

An 11-y prospective follow-up study conducted among 683 men from the Kuopio Ischaemic Heart Disease Risk Factor Study who were 42 to 60 y old at baseline in 1984 to 1989. The main outcome was incident metabolic syndrome, defined by the National Cholesterol Education Program (NCEP) criteria. Other outcomes were the individual components of the NCEP metabolic syndrome: Fasting blood glucose, serum triacylglycerols, serum high-density lipoprotein (HDL) cholesterol, hypertension, and waist circumference.

RESULTS

During the average follow-up of 11 y, 139 men (20.4%) developed metabolic syndrome. Those in the highest tertile of serum zinc had 84% higher risk (95% confidence interval 12 to 201%, P trend across tertiles = 0.015) to develop metabolic syndrome compared with those in the lowest tertile, after adjustment for several potential confounders. The association between serum zinc and incident metabolic syndrome was attenuated by adjustment for waist circumference, serum HDL cholesterol, or hypertension. Serum zinc was also directly associated with higher waist circumference and hypertension and inversely associated with HDL cholesterol at the 11 y examinations.

CONCLUSIONS

We found a direct association between serum zinc and incidence of metabolic syndrome in middle-aged and older eastern Finnish men. Further studies are warranted to explore the mechanisms.

Effects of Oral Administration of CrCl3 on the Contents of Ca, Mg, Mn, Fe, Cu, and Zn in the Liver, Kidney, and Heart of Chicken

This study aimed to investigate the effects of oral administration of trivalent chromium on the contents of Ca, Mg, Mn, Fe, Cu, and Zn in the heart, liver, and kidney. Different levels of 1/8, 1/4, and 1/2 LD50 (LD50 = 5000 mg/kg body mass) CrCl3 milligrams per kilogram body mass daily were added into the water to establish the chronic poisoning model. Ca, Mg, Mn, Fe, Cu, and Zn were detected with the flame atomic absorption spectrometry in the organs exposed 14, 28, and 42 days to CrCl3, respectively. Results showed that Cr was accumulated in the heart, liver, and kidney significantly (P < 0.05) with extended time and dose. The contents of Ca and Fe increased, whereas those of Mg, Mn, Cu, and Zn decreased in the heart, liver, and kidney of each treated group, which had a dose- and time-dependent relationship, but the contents of Mg and Zn in the heart took on a fluctuated change. These particular observations were different from those in the control group. In conclusion, the oral administration of CrCl3 could change the contents of Ca, Mg, Mn, Fe, Cu, and Zn in the heart, liver, and kidney, which may cause disorders in the absorption and metabolism of the metal elements of chickens.

Serum zinc and risk of type 2 diabetes incidence in men: The Kuopio Ischaemic Heart Disease Risk Factor Study

OBJECTIVES

Zinc may play a role in the development of type 2 diabetes (T2D), because it is involved in antioxidant and anti-inflammatory activities. However, the role of zinc in the etiology of T2D has been poorly investigated. This study was conducted to study the association of serum zinc on T2D risk in middle-aged and older Finnish men.

METHODS

This was a 20-year prospective follow-up study on 2220 Finnish men from the Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD) who were 42 to 60 years old at baseline in 1984-1989. The main outcome was incident T2D. Serum zinc, body mass index (BMI), fasting blood glucose (FBG), serum insulin, C-reactive protein (CRP) and, in a subset of 751 participants, insulin-like growth factor-binding protein-1 (IGFBP-1), were measured. Also, the homeostatic model assessment (HOMA) was used to quantify insulin resistance (HOMA-IR), beta-cell function (HOMA-β) and insulin sensitivity (HOMA-IS).

RESULTS

At baseline, serum zinc was associated with higher BMI, serum insulin, HOMA-IR, HOMA-β and IGFBP-1 and lower HOMA-IS. During the average follow-up of 19.3 years, 416 men developed T2D. Men in the highest quartile of serum zinc had 60% higher risk (95% CI 20-113%; P-trend<0.001) for incident T2D compared with the men in the lowest quartile, after multivariate adjustments. This association was attenuated after adjustment for BMI (HR=1.39, 95% CI 1.04-1.85; P-trend=0.013) or HOMA-IS (HR=1.38, 95% CI 1.04-1.83; P-trend=0.015), whereas adjustment for the other factors had only modest impact on the association.

CONCLUSION

Higher serum zinc was associated with higher risk of T2D; effects of zinc on BMI and insulin sensitivity may partly explain the association. Further prospective studies are warranted to confirm our results and explore potential mechanisms.

Advances in understanding the interrelations between leptin resistance and obesity

Obesity, which has developed into a global epidemic, is a risk factor in most chronic diseases and some forms of malignancy. The discovery of leptin in 1994 has opened a new field in obesity research. Currently, we know that leptin is the primary signal from energy stores and exerts negative feedback effects on energy intake. However, most individuals with diet-induced obesity (DIO) develop leptin resistance, which is characterized by elevated circulating leptin levels and decreased leptin sensitivity. To date, though various mechanisms have been proposed to explain leptin resistance, the exact mechanisms of leptin resistance in obesity are poorly understood. Consequently, it's an important issue worth discussing regarding what the exact interrelations between leptin resistance and obesity are. Here, we review the latest advancements in the molecular mechanisms of leptin resistance and the exact interrelations between leptin resistance, obesity, and obesity-related diseases, in order to supply new ideas for the study of obesity.

Attenuation of Zn-induced hyperleptinemia/leptin resistance in Wistar rat after feeding modified poultry egg

BACKGROUND

The prevalence of obesity is increasing exponentially world over. Leptin resistance/hyperleptinemia is attributed to its cause in majority of the obese humans where mutation in genetic component or ob gene has not been found operative. The generation of oxidative stress was suggested as its cause. In our previous study, we have reported that the inclusion of antioxidant enriched modified poultry egg (ME) in diet reversed the ionic imbalance and ameliorated the oxidative stress caused by excessive Zn in diet. In the present study, the efficacy of ME verses conventional egg (CE) was tested on Zn-induced leptin resistance in rat model to ascertain if the supplementation of antioxidants in the form of egg can reverse Zn-induced leptin resistance to leptin sensitive state.

METHODS

Hyperleptinemia was induced in rats by feeding them Zn-supplemented hyperleptinemic diets-I and II (Zn-HL-Diet) for 2 months. Thereafter, half of them were fed either on CE or ME mixed Zn-HL-diets I and II for another two months. The data was analyzed applying one way Anova and Tukey's HSD post hoc test.

RESULTS

The results revealed that food intake, gain in body weight, height and number/unit surface area of intestinal microvillus and serum leptin, glucose, insulin and cortisol were higher in CE and Zn-HL-Diet treated groups; serum Zn, Cu, Mg were higher and Cu and Mg in tissues were lower in them than the control group. In ME treated groups, these parameters were lower and were close to the control group. These changes resulted from the restoration of ionic balance of Zn, Cu and Mg in the blood serum and tissues including liver and hair in ME treated rats.

CONCLUSION

The data suggest that Zn-induced leptin resistance can be attenuated through restoring the ionic balance of Zn, Cu and Mg through inclusion of antioxidants in diet such as these modified eggs. But further clinical studies are required before they are put to use for human consumption.